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Apollo 10

NASA prints 24,791 mph at entry interface on 26 May 1969, relative to Earth. Guinness prints 39,937.7 km/h for a later peak on the same entry.

Also known as Charlie Brown
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Velocity

Published as 24,791 mph

Entry interface at 400,000 feet on the trans-Earth return, relative to Earth. NASA prints 24,791 mph. Guinness prints 39,937.7 km/h (24,816.1 mph) from a later 36,397 ft/s maximum on the same entry.

OfficialNASA (opens source in a new tab)

In context

  • Once around Earth in 1 hConstant · Earth's equator, 40,075 km (WGS 84)
  • London to New York in 8 minConstant · London to New York, 5,570 km great-circle
  • 37% of Earth's speed around the SunSourced · Earth, 29.8 km/s. NASA planetary fact sheet, mean orbital speed

Worked out from the sourced figure above, which stays the ranked number.

Mechanism

Why it's so fast

Apollo 10 is fast in a frame you have to name. A rocket does not need to breathe the air, and a spacecraft's big speeds come from burns and from falling in a gravity field.

  1. Say what the speed is relative to

    Speed relative to the Sun, to Earth, or to the air are different measurements. The entry keeps the frame in the conditions. Mixing them would invent a comparison.

  2. Gravity or a burn

    Apollo 10 gets its ranked speed from the burn or the fall the sources describe. This note does not add a delta-v the papers did not print.

Nearby on this list: New Horizons.

Provenance

Every measurement

Claimed, measured and official figures side by side, each with its source. The ranked figure is marked.

  1. 11.08km/s24,791mphRanked figure

    Entry interface at 400,000 feet on the trans-Earth return, relative to Earth. NASA prints 24,791 mph. Guinness prints 39,937.7 km/h (24,816.1 mph) from a later 36,397 ft/s maximum on the same entry.

    Wikipedia prints 39,897 km/h (24,791 mph), which matches NASA. Guinness's 39,937.7 km/h is the higher maximum of 36,397 ft/s during the entry, not the interface speed.

    Official
    NASA (opens source in a new tab)

Reference

Specs

Frame
Relative to Earth
Crew
Stafford, Young, Cernan
NASA figure
24,791 mph at entry interface
Date
26 May 1969

Context

Background

This list is speed relative to Earth. It is not the heliocentric list that ranks the Parker Solar Probe. NASA's history of Apollo 10 prints 24,791 miles per hour at entry interface, 400,000 feet, on the return of 26 May 1969, and calls it the fastest reentry of a crewed mission. Wikipedia prints 39,897 km/h (24,791 mph) for that same Earth-relative mark. The ranked figure is NASA's 24,791 mph.

Guinness prints 39,937.7 km/h (24,816.1 mph) and ties it to 36,397 ft/s. A mission-report summary distinguishes that later maximum from the speed at 400,000 feet, about 36,314 ft/s. The two numbers are different points on one entry, not a rounding of each other. NASA's interface figure is the rank. The Guinness peak is the note.

Spot a wrong number?

Every report is read by a person, and corrections are dated on the page.